2, 5-bis (p-aminophenyl) furan azo derivatives



Unite States Patent C 2,5-BIS(P-AM]NOPHENYL) FURAN AZO DERIVATIVES 8 Claims. (Cl. 260152) This invention relates to new compounds of the diphenyl furan series and more specifically to compounds of the structure:

Ri\ /Rl N Ar Ar-N O I R X X R:

in which R is hydrogen, acyl or alkyl, R is hydrogen or alkyl, X is hydrogen or a sulfonic acid group, and Ar is a radical of the benzene or naphthalene series. These compounds in which R R N is para to the furan bond, are useful as brighteners or ultraviolet absorbers and as intermediates for these products, dyes, pigments, etc.

The simplest example of a compound of this type, viz. 2,5-bis(para-aminophenyl)-furan, is a valuable intermediate from which dyes, pigments, brighteners and ultraviolet absorbers for plastics and other uses may be prepared. For example, the acyl derivatives of this diamine, as well as its sulfonated derivatives, possess fluorescence and can be used as brighteners. The sulfonated derivatives are particularly useful in this respect because they are water-soluble and have affinity for cellulosic materials. The N,N-dialkyl derivatives have less ailinity for cellulosic materials but can be used as ultraviolet absorbers in plastics and to whiten materials such as wool, nylon, and acetate. For such uses the unsulfonated compounds are often preferable. Alternatively, the amino groups of 2,5-bis(para-aminophenyl)-furan can be diazotized and coupled to give azoic dyestuffs and pigments. The sulfonated derivatives can be similarly treated to produce azo dyes.

In our method of preparing 2,5-bis(para-aminophenyl)- furan, fumaryl chloride is condensed with acetanilide to give 1,2-bis (para-acetamidobenzoyl)-ethylene. The latter compound is then ring closed with simultaneous introduction of the required two hydrogen atoms by treatment with a mixture of hydrobromic acid, acetic acid and betanaphtliol. The resultant 2,5-bis(para-acetamidopheuyD- furan can beconverted to the free diamine by hydrolysis with aqueous-alcoholic HCl. Other methods of preparation, for example, cyclization of l,2-bis(para-acetamidobenzoyl)-ethane, are, of course, apparent.

Some of the uses for this new compound require that the molecule be sulfonated. This can be done in two ways. When a 2,5-bis(acylaminophenyl)-furan is sulfonated in concentrated sulfuric acid under mild conditions, a mono-sulfonie acid results. It is most surprising that this sulfonation can take place since furans are believed to be destroyed by strong acids unless stabilizing negative substituents are present. The fact that only one sulfonic acid group is introduced under such mild condi tions indicates that sulfonation is occurring in the furan ring in the 3-position.

If, instead of sulfonation in strong sulfuric acid, the sulfate of the free diamine is baked, disulfonation occurs. These sulfonic groups are believed to be in the phenyl rings, probably ortho to the amino groups. We do not wish to be limited however to any theory as to the location of the sulfoni-c acid groups because there is no proof as to their identity. It is possible, for example, that rearrangement of the sulfate results in the introduction of one sulfo group in the furan ring and one in the expected ortho position in the benzene ring.

To obtain water-soluble brighteners, the bis(paraaminophenyl)-furan-disulfonic acid can be acylated or the unsulfonated bis(para-aminophenyl)-furan can be first acylated and then sulfonated in concentrated sulfuric acid to give the mono-sulfonic acid derivative. Such acylation can be carried out with any of the acylating agents com monly used, such as benzoyl chloride and its alkyl, alkoxy and acylamino derivatives. Examples of the latter are para methoxybenzoyl chloride, ortho methoxybenzoyl chloride, 2,4-dimethoxybenzoyl chloride, 2,4-diethoxybenzoyl chloride, ortho-toluyl chloride, para-toluyl chloride, para-acetamidobenzoyl chloride, para-benzamido benzoyl chloride, Z-methoxy-4-methylbenzoyl chloride and the like.

To obtain azo dyes the bis(para-aminophenyl)-furan and its sulfonic acid derivatives can be diazotized and coupled to any selected coupling component such as phenols, naphthols, aminophenols, aminonaphthols, naphtholsulfonic acids, aminonaphtholsulfonic acids and the like. When the unsulfonated diamine is used, azoic dyes and pigments can be prepared by coupling with unsulfonated phenols, naphthols, amines, oxynaphthoic arylides, acetoacetarylides and the like. Stabilized tetrazos can be prepared by coupling the tetrazo to alkylamino sulfonic or carboxylic acids. These can be used with the various naphthols such as oxynaphthoic arylides. The coupling products which contain no sulfonic acid groups can also be used as pigments.

Of particular value in the dyestuff field are the diaminodiarylfurans containing metallizable groups o-rtho to the amino groups. The term metallizable groups includes hydramyl, carboxyl, halogen, alkoxy, OCH COOH and SCH COOH. When these groups are present the azo dyes obtained can be converted to metal complexes. These complexes are particularly useful for the dyeing of cotton and rayon in attractive shades and are much faster to light than the unmetallized dyes. The most stable and useful complexes are those derived from dyes in which the coupling component also contains a metallizable group ortho to the azo linkage. Generally, copper is the most useful metal but other metals may be used, especially nickel, cobalt, iron and chromium. Again, using an unsulfonated diaminodiphenylfuran and unsul-fonated coupling components, azo pigments may be obtained and in these cases may be metallized to yield unique shades of improved fastness.

These new intermediates may be made by the same general precedures outlined above. Thus, using acetcresidide there is obtained 2,5-bis(2-methyl-4-amino-S-methoxyphenyD-furan. Other useful starting materials are o-aminophenol diacetate, N-a-cetyl-2-aminophenoxyacetic acid, acet-o-chloranilide, N-acetyl-Z-methoxy-S-chloroaniline, N-acetyl-Z,S-dimethoxyaniline and the like.

Another important aspect of our invention is that compounds of the naphthalene series may be prepared. For example, by the same general preparative methods one can obtain 2,5-dinaphthylfurans containing amino groups para to the bonds to the furan ring. For example N- acetyl derivatives of a-naphthylamine and derivatives lead to compounds of the following type:

and by using acetyl derivatives of compounds such as l-amino-2-ethoxynaphthalene, l-ain'ino 2,6 dimethoxynaphthalene, l-arnino-Z-naphthol, l-amino-Z-naphthoic acid and l-amino-2-naphthoxyaceti acid new intermediates are obtained which are useful for the preparation of metallized dyes and pigments. Obviously, these compounds can also be sulfonated, in fact usually more readily than the corresponding benzene derivatives.

Brighteners containing basic substituents, and useful for non-cellulosic materials such as wool, nylon, and acetate as well as for incorporation in plastics, can be prepared by alkylating 2,5-bis(para-aminoaryl)-furans, using alkylating agents such as dialkyl sulfates or alkyl halides. The properties of the products will depend on the size of the alkyl group, since the larger the alkyl group the greater is the solubility to be expected in plastics. xamples of the alkyl groups which can be used are methyl, ethyl, propyl, butyl, octyl, dodecyl, octadecyl. One can also use a'ralkyl groups such as benzyl and substituted benzyl groups. The dialkyl sulfate is preferably used when lower alkyl groups are being introduced, but with the higher alkyl groups, the halides are usually more available. Alternatively, one can synthesize the diaryl fu'ran system with the alkylamino groups already in place by starting with an N,N-dialkylaminobenzene or naphthalene or with an acylated secondary amine of the same type.

It is very surprising that this ring system is such a useful one. It could not be predicted that derivatives of bis(para-aminoaryl)-furans would fluoresce at all. Still less could it be predicted that such fluorescence would occur in the wave lengths necessary to make good brighteners. Similarly, it was impossible to predict that the sulfonated dyes derived from the tetrazotized diamines would be substantive to cellulosic materials under direct dyeing conditions.

Our invention can be further illustrated by the following examples in which parts are by weight unless otherwise indicated.

Example 1 4 shows a moderate greenish white solid fluorescence which becomes 'iilf'fi'sly blfiish 'iil solution.

If, in Example 1, propionanilide or butyranilide is used as the starting material instead of acetanilide, the products, treated as above, will give the propionyl or butyryl derivatives corresponding 'to the acetyl derivative above.

Example 3 A mixture of 10 parts of the product of Example 2 and 60 parts of alcohol is stirred at reflux. Thirty-six parts of concentrated hydrochloric acid is then added gradually and the mixture is refluxed until hydrolysis is complete. The mixture is then cooled and the product is isolated by filtration. It is then taken up in boiling water and precipitated by careful basification with sodium hydroxide. The product is isolated by filtration and washing. This crude product can be recrystallized from alcohol to yield light tan crystals, melting point 216.0- Z16.8 C., which give the correct analysis. 1

Example 4 The procedure of Example 1 is followed, using lJ-octa decyl acetanilide in place of the acctanilide. The product is then ring-closed by the procedure of Example 2 to give 2,5-bis (p-octadecylacetylaminophenyl) furan. This is then hydrolyzed by the procedure of Example 3 to give 2,5-bis (p octadecylaminophenyl) furan.

Similarly, by starting with N-butylacetanilide, N-laurylacetanilide, N benzylacetanilide, or N-ethylacetanilide, the corresponding butyl, lauryl, benzyl, or ethyl derivatives are prepared.

A mixture of 53.2 parts of aluminum chloride and 208 parts of symmetrical tetrachlorethane is cooled below 5 C. 29.8 parts of acetanilide is then added followed by the gradual addition of a mixture of 15.3 parts of fumaryl chloride and 48 parts of symmetrical tetrachlorethane. The mixture is then slowly heated to about 70 to 80 C. and held there until the reaction is complete. The mixture is cooled and drowned on 1000 parts of ice mixed with parts of concentrated hydrochloric acid. The organic layer is thoroughly washed by decantation and the solvent is then removed by steam stripping. The solid product which remains is slurried in alcohol, filtered, and washed with alcohol. By recrystallization from acetic acid a product of good purity having a melting point of 278 C. is obtained.

Example 2 T o 525 parts of a solution of I-IBr in glacial acetic acid is added 26.2 parts of the crude product from Ex ample 1 and 16.2 parts of beta-naphthol. The mixture is stirred at room temperature until the reaction is complete. It is then drowned on ice and the drowned slurry is basified with sodium hydroxide. During this basification the temperature is kept down to prevent decomposition. The product is isolated by filtering and washing, and purified by extraction with hot alcohol. The crude product can be recrystallized from boiling glacial acetic acid to produce lustrous light tan crystals melting at 307 308 C. This purified product gives a good analysis and V Exainple 5 egg g on;

/ JQ CH CHz The procedure of Example 1 is followed using dimethyl aniline instead of acetanilide. The product is ring-closed by the procedure of Example 2 to form 2,5-bis (p-dimethyl'afr'iiriophenyl) fura'n.

Example 6 The procedure of Example 1 is followed, using N- ace'tyl alphanaphthyla'mine in place of the acetanilide. The resulting product is ring-closed by the procedure of Example 2 and hydrolyzed by the procedure of Example Example 7 CH3 CH3 CH: CH:

Example 11 O CzHs O C2Hu The procedure of Example 1 is followed, using acetcresidide instead of acetanilide. The product is ringclosed by the procedure of Example 2 and hydrolyzed by the procedure of Example 9 to give 2,5-bis (l-methyl-4- amino-S-methoxyphenyl) furan.

Example 8 HaN -NH2 A mixture of 5 parts of the product of Example 3 and 50 parts of pyridine is stirred at the boil while 13.3 parts of ortho-ethoxybenzoyl chloride is added gradually. The mixture is then stirred at the boil until acylation is complete. The solvent is removed under pressure and the residue is taken up in 100 parts of water and 10.6 parts of sodium carbonate. The mixture is then boiled until all traces of the pyridine are removed. When it has cooled to room temperature the light tan solid is isolated by filtration and Washing, and is dried. The crude product can be recrystallized from pyridine to produce a pure, faintly yellow crystalline solid with intense solid fluorescence, melting at 259-260 C.

Example 12 using N-acetyl-o-amino-phenoxyacetic acid as the starting material in place of acetanilide. The product is 2,5- bis (4-amino-3-carboxymethoxyphenyl) furan. Similarly, if N-acetyl-o-aminophenyl-thioglycollic acid is used as the starting material, 2,5-bis(4-amino-3-carboxymethylmercaptophenyl) furan is produced. By using l-acetyl- CHWQO O-NH amino-Z-naphthyloxyacetic acid, there is similarly produced 2,5-bis(4-amino 3 carboxymethoxynaphthyl-l-) furan.

Example 9 Fifty parts of 100% sulfuric acid is cooled while 8.35 parts of the product of Example 2 is added gradually.

The mixture is then allowed to stir at room temperature Example 10 A mixture of 7.4 parts of the product of Example 9 and parts alcohol is held at reflux while 24 parts of The procedure of Example 11 is followed substituting 13.6 parts of anisoyl chloride for the ortho-ethoxy benzoyl chloride of that example. The product can also be recrystallized from pyridine to give a nearly colorless solid with intense bluish-white solid fluorescence, melting point 317-318 C.

Example 13 Forty parts of concentrated sulfuric acid is cooled and stirred while 10.4 parts of the product of Example 12 is added gradually. The mixture is then allowed to stir until sulfonation is complete. One hundred parts of cracked ice is then added and the precipitated light yellow solid is isolated by filtration. It is boiled briefly in about 50 parts of water and re-isolated by filtration. The solid is then slurried in 200 parts of water and heated to boiling. The hot solution is made slightly alkaline with sodium carbonate and salted with sodium chloride. A. faintly yellow granular solid separates and, after cooling, the product is isolated by filtration and washing. This material shows an intense greenish-yellow solid fluorescence and an intense bluish-white solution fluorescence. Analytical data indicates the product is a monosulfonic acid, presumably having the above structure.

The product of Example 11 can be similarly sulfonated.

Example 14 SOaNa S OsNa Five parts of the product of Example 3 is mixed with 60 parts of dichloro-benzene and the mixture is stirred at 140 C. while 4.12 parts of sulfuric acid is added gradually. The temperature is then raised to reflux and the mixture is refluxed until sulfonation is complete. It is then cooled and 250 parts of water containing 8.9 parts of sodium carbonate added. The dichlorobenzene is removed by steam distillation and the residual slurry is coupling components suchas beta-naphthol, Z-hydroxyclarified at the boil by filtration and washing with hot 3-naphthoic acid and its aryl'idcs, arylides of acetoacetic water. The; filtrates are concentrated to approximaely acid, and pyrazolones such as 1-phenyl-3-methy1 pyrazo- 50 parts by volume and salted with 50 parts ofsaturated l ne-5 are used, the colfespmlding aZO Pigments are brine. The cooled mixture is. filtered to isolate the solid 5 obtained. I

brown product. Analytical data establishes the presence V If, instead of the product of Example 3, the product of of two sulfonic acid groups. For convenience, these are Example 7 or 8 is used, the dye so obtained can be assumed to be in the benzene rings as indicated above, but metallized with copper or chromium to give much faster thisstructure has notbeenproven. shades. Such metallization can be carried out before Example GH:O5-C0NH- O -Q -NHC OQ-O on;

sohNa SOaNa A mixture of 4.48 parts of the product of Example 14 application to the cloth or (in the cas'e'of the product and 30 parts of pyridine is refluxed while there is added derived from Example 8) after application to the cloth. gradually 6.44 parts of anis'oyl chloride. The mixture is then stirred at reflux until the acylation is complete. 2.12 parts of sodium carbonate is added and the pyridine 503E 801E N N J U Example 18 is removed by steam distillation. The residual mixture is then basified' by adding- 2 parts moreof sodium car humans. It is then diluted with water to a total of 300 parts by volume and heated to the bell. The solution is clarified hot and the boiling filtrate is salted with 21.4 parts of sodium chloride. The mixture is then cooled and the solid product is isolated by filtration and drying. It is a light brown powder which can be recrystallized from boiling Water with a charcoal treatment followed by resalting to give a much purer product.

-..o1r no Diaminodiphenyl furan disulfonic acid, prepared as described in Example 14, was diazotized and coupled with beta-naphthol according to the procedure of Example 16.

The product was isolated as usual and found to dye Exam-P1816 when and rayon a bright, reddish blue shade.

The product of Example 3 was tetrazotized in the S Varying O fi Y Q f blue red or usual manner and the resultant solution was used to. dye Vlolet may be obtalnefli by using up l mmpollefiis cloths which had previously been prepared in the stand- 1? aceioacetafyhdesi -PY -P Y ard manner with various naphthols. The following m hy l-5-py n acy'leceidnitriles. flrylid'es of shades were obtained from the compounds indicated: 2-hydroxy-3-naphthoic"acid. I I Napht'hol AS-OL, 3-hydroxy-2-naphthoic-o-anisidide 40 results .Obtamed 1f the l l violet furan monosulfomc acid of Example 10 is used in place Naphthol A343, 3 hydroxy z naphthoic p chloranmde of the disulfonic acid. The product differs primarily in blue violet solub1lity.

. hthl S- N,N'-b' t 1 -t lid'd 11 We claim; E-an; A G mace oacety-o e ye OW 1. Compounds of the formula:

Naphthol AS1G, Z-hydroxy-ll-benzo [a] carbazole-3- carbox-p-anisidide-blue gray I Naphthol- AS-BR, 4,4'-bis(3-hydroxy-2-naphthoylarnino)- 3,3'-dimethoxydiphenyl-light violet 0 Example 17 OH HO H035 03H I H038 0311 A slurry of 1.04 parts of the product of Example 3 in in which Ar is an aryl radical of les's than three six- 20 parts of a solution containing" 3 parts by volume of membered carbocyclic rings, the said rings being fused concentrated hydrochloric acid was diazotized at 10 C. when there are two such rings, the are linkage being'on with 0.566 part of sodium nitrite. The solution of the the same'ring in Ar as, and para to, the furan linkage, diazonium salt was added to a solution of 3.16 parts of and in which R is a-coupling com onent. 2-naphthol-3,6-disulfonic acid sodium salt in aqueous 2 Compounds of claim 1 inwhich Ar 1s monocychc. caustic at 10 C. and maintained weakly alkaline until 3. Compounds of claim lin which Ar 1s anaphthale'ne coupling was complete. The coupling product was filradical. tered off and purified by reprecipitation by means of 4. Compoundso'f cla1m'21nwh1chthe sodium acetate from solution in a caustic-pyridine mixture. The product dyed cotton a bright reddish blue 7 shade. A A

In the same manner, the above tetrazo compound can r 0 be reacted with other sulfonated azo coupling components such as 2-naphthol-6,8-disulfonic acid, 2-naphthol-6" part of the molecule is sulfonated. sulfonic acid, andZ-naphthol-S-sulfonici acid to formthe' 5. Compounds of claim 4 in which the Ar radicals other corresponding direct dyes. If unsul fo'nated are are's'ulfonated.

6. A compound having the formula:

N=N N=N QUQ I OH OH COHNQ COHNQ 7. A compound having the formula:

H018 03H HOaB SOIH References Cited in the file of this patent 8. A compound having the formula: UNITED STATES PATENTS 2 413 248 Senkus Dec. 24 1946 O H J ME 8 25 2,598,333 Zerbe May 27, 1952 N=N 2,641,597 Goldberg et 'al June 9, 1953 0 l 2,653,928 Graenacher et a1. Sept. 29, 1953 OH HO OTHER REFERENCES 30 Guyot et al.: Annales de Chemie, Huitieme Series,

P. 316, Tome 19 (1910). 

1. COMPOUNDS OF THE FORMULA: 